This invention relates to a hydrocarbyl polyoxyalkylene urethane and to an internal combustion engine fuel composition containing same.
The combustion of fuel in an internal combustion engine typically results in the formation and accumulation of deposits on various parts of the combustion chamber and on the fuel intake and exhaust systems of the engine. The presence of these deposits in the combustion chamber often result in the following problems: (1) reduction in the operating efficiency of the engine; (2) inhibition in the heat transfer between the combustion chamber and the engine cooling system; and (3) reduction in the volume of the combustion zone which can cause a higher than design compression ratio in the engine. A knocking engine can also result from deposits forming and accumulating in the combustion chamber. A prolonged period of a knocking engine can result in stress fatigue and wear in engine components such as, for example, pistons, connecting rods bearings and cam rods.
The formation and accumulation of intake valve deposits can interfere with valve closing which eventually can result in valve burning. Such deposits can also interfere with valve motion and valve seating which tend to reduce the volumetric efficiency of the engine and limit the maximum design power.
Deposits can also collect in the tubes and runners that are part of the exhaust gas recirculation (EGR) flow. The collection of these deposits can reduce the EGR flow. This will result in a knocking engine and an increase in nitric oxide emissions.
In view of the foregoing problems associated with the formation and accumulation of deposits in the combustion chamber and fuel intake and exhaust systems of an internal combustion engine, efforts have been made to develop fuel additives which will inhibit the deposition of deposits in the engine. Illustrative of such fuel additives are the amino alkanolamines of U.S. Pat. Nos. 5,234,478 and 5,383,942 and the alkylphenoxypolyoxyalkylene amine lactones of U.S. Pat. No. 5,527,364.